The present invention relates to tension control devices for a printing press.
Before the present invention, multi-color printing units have been used in a printing press to print colored images on a paper web. The webs used in the press unwind the web from a supply roll. Due to the relatively fast speed of the press, the rolls have been completely unwound in a relatively short period of time, such as 15 minutes.
In accordance with prior practice, a new roll of the web is pasted onto the web of the previous roll when it is almost depleted. However, the rolls each have different characteristics, such as different manufacture and different winding tensions. As a result, the tension on opposed sides of the new web becomes significantly different, causing loss of registration in the press, and flapping of the web which may cause a web break.
Adjustments must be made to the press in the event of loss of registration, and due to the relative frequency of web pasting This factor results in loss of press time, wasted product, and inconvenience to the operator of the press.